This invention relates to beds, and it particularly relates to improvements in mattress configurations and the decks and related structures for supporting mattresses.
The principal applicability of the invention is in storable bed structures such as sofa sleepers, rollaway beds, bunk beds and cabinet beds. Modern lifestyles often involve smaller homes, modest condominiums and apartments. This has created an increasing utilization of storable units that convert into beds. Previously, when such storable beds were used only for occasional guests, the comfort of such units was of secondary importance; however, as such units are now being used more frequently on a daily basis, the need for acceptable comfort levels is much greater.
A storable bed unit normally uses a thin mattress with flat upper and lower surfaces. The mattress is supported on a deck which has its perimeter connected to a foldable peripheral frame by means of helical springs or other tension elements. The decks are normally formed of a flexible metal mesh called "link fabric" or a textile fabric which has border wires sewn therein, an example of the latter being disclosed in my U.S. Pat. No. 4,326,260. Frames may be formed of tubular metallic sections, metal angles or a combination of such components.
A recognized problem of storable bed units is that they tend to sag or "hammock" to the center of the sleeping surface. This is particularly true in units where mattresses are very thin because they are required to fold into three thicknesses. The industry has recognized that there are glaring deficiencies in the sleeping comfort of such units, resulting in the rejection of such units at the retail level.
A number of solutions have been proposed to the sagging problem. One proposal is to increase the thickness of the mattress, but this introduces additional problems with respect to units such as sofa sleepers. The increased mattress thickness may raise the seating height to an unacceptable level. Due to the floor clearances required for the mechanisms of such units, thicker mattresses may require an increase in the front-to-rear depth of the unit to an extent which is aesthetically unacceptable.
Other efforts to avoid or diminish the sagging problem have involved an increase in the deck tension by adding tensioned wires, straps, rubber webbing or extra helical springs. It has also been proposed to modify the mattress structure so that it has areas of varying compressibility or density. These efforts add to the cost of such units and they have been used to some degree with limited results.
Another approach has been to provide the units with transverse wooden slats which are bowed upwardly. Beds of this nature have not been introduced in this country, at least to any significant extent, probably due to the increased cost of such construction. Another proposed but costly solution is to provide a deck which has a localized depression in the buttock area, and to provide a mattress with a localized protruberance on its lower surface for insertion in the depression.
It is believed that the present invention offers a superior solution to the sagging problem. It is superior in the sense that it does not increase significantly the cost of manufacture of the components of the system. In a sofa sleeper unit, the invention provides improved comfort during sleep while, at the same time, providing acceptable seat height, acceptable seat pitch, and acceptable travel clearances relative to the floor without significantly increasing the front-to-rear depth of the unit.